Fluid handling – Systems – Supply and exhaust
Patent
1996-12-20
1998-04-07
Michalsky, Gerald A.
Fluid handling
Systems
Supply and exhaust
60452, 91446, F15B 1105
Patent
active
057353115
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a pressure compensation valve for use in a hydraulic circuit, e. g. a hydraulic circuit for supplying a discharge pressure fluid from one or more hydraulic pumps to a plurality of actuators in distributed flow rates in a construction machine.
BACKGROUND ART
If it is attempted to supply a discharge pressure fluid from a hydraulic pump to a plurality of actuators, it has generally been known that the pressure fluid tends to be admitted only to an actuator of the lowest load pressure. In order to resolve this problem, it has been known to make use of a certain hydraulic circuit, for example, as disclosed in Japanese Unexamined Patent Publication No. Sho 60-11706. In such a hydraulic circuit, a pressure compensation valve is provided, respectively, at the inlet side of a directional control valve that is arranged for each of the actuators. More specifically, this is a hydraulic circuit in which each of the pressure compensation valves is set for the highest of different load pressures which are met by the respective actuators so that a plurality of actuators of the varying load pressures may be fed with a discharge pressure pressure with distributed flow rates.
An example of the pressure compensation valve which can be used in such a hydraulic circuit has been known that is disclosed, for example, in Japanese Unexamined Patent Publication No. Hei 4-244605.
This is a pressure compensating valve in which as shown in FIG. 1 of the drawings attached hereto, a valve body 1 includes a check valve portion 5 that is provided with a check valve bore la having an inlet port 2 and an outlet port 3, the said check valve bore la having a valve 4 slidably fitted therein for establishing and blocking a communication between the inlet port 2 and the outlet port 3. The above mentioned valve body 1 also includes a pressure reduction valve portion 12 that is provided with a pressure reduction valve bore 1b having a first port 6, a second port 8 and a third port 9, the said pressure reduction valve bore 1b having a spool 11 slidably fitted therein and having at its two ends, respectively, a first pressure chamber 7 that communicates with the first port 6 and a second pressure chamber 10 that communicates with the third port 9 and in which under a pressure in the first pressure chamber 7 the above mentioned spool 11 is thrusted rightwards for establishing a communication between the second port 8 and the third port 9, and under a pressure in the second chamber 10 the said spool 11 is thrusted leftwards for blocking the communication between the second port 8 and the third port 9. At this point it should be noted that the above mentioned spool 11 is designed to be thrusted by a spring 13 in such a direction as to block the communication between the second port 8 and the third port 9 and then for abutment on the above mentioned valve 4. And, the said pressure compensation valve is constituted of these components.
If such a pressure compensation valve is adopted, it can be seen that when a pressure within the first pressure chamber 7 is higher than a pressure within the second pressure chamber 10, the said spool 11 will be displaced rightwards to depart from the valve 4 and to position the valve 4 so as to make a pressure in the inlet port 2 equal to a pressure in the outlet port 3. As a result, it can also be seen that a pressure within the first pressure chamber 7 and a pressure within the second pressure chamber 10 will be made equal to each other. On the other hand, it can be noted that when a pressure within the first pressure chamber 7 is lower than a pressure within the second pressure chamber 10, the valve 4 will be thrusted with the spool 11 into its blocking position so that the pressure in the outlet port 3 may be made lower than the pressure in the inlet port 2 by a pressure difference between the second pressure chamber 10 and the first pressure chamber 7.
This being the case, it can be seen that by connecting the outlet port 3 to a pump port 15 of a directional contro
Akashi Mitsumasa
Ishizaki Naoki
Kananen Ronald P.
Komatsu Ltd.
Michalsky Gerald A.
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